In a semiconductor test system for testing semiconductor devices, a test signal pattern called a test vector is provided to a semiconductor device under test and a resultant output from the semiconductor device is compared with an expected value signal established in advance to determined whether the semiconductor device under test works correctly or not. Generally, the test vector is produced through a test program. The languages in the test program are unique to manufacturers of the semiconductor test system and vary from manufacture to manufacture. To sufficiently test complicated computer chips or large scale semiconductor memories, for example, a semiconductor test system must perform complicated and sophisticated test at high speed. Therefore, an actual structure of the semiconductor test system is a structure of a large scale computer system. Consequently, a large scale software including the above noted test program is used to control the test and other operations of the semiconductor test system.
In the semiconductor production industry, there is a strong demand to improve efficiency of a semiconductor test system. This is because that a recent semiconductor test system is a complicated and expensive system and price competition of semiconductor devices is fierce. Therefore, an exclusive use of the semiconductor test system for a process such as producing a test program for semiconductor devices to be tested must be avoided. Further, it is desired that the newly produced test program in such a process be evaluated and confirmed without using the hardware of the semiconductor test system.
As a consequence, in a modern, high end semiconductor test system, an emulator is frequently employed. However, in a conventional semiconductor test system, an emulator is only to emulate an operating system of the semiconductor test system, and thus, its function is not sufficient. For example, the conventional emulator is not able to perform the level of emulation in which the test for a specific semiconductor device is executed by applying test vectors to the semiconductor device to be tested and analyzing the resultant signals from the device.
Because of the rapid improvement in the technology of the semiconductor devices, a semiconductor test system for testing such rapidly changing semiconductor devices is frequently required to be expanded, modified or replaced with a new model. For example, in a test pattern generator of a semiconductor test system which generates test vectors to be applied to semiconductor devices under test, in addition to the function of generating a test pattern of a relatively normal and simple sequence, an algorithmic pattern generator may be added to generate a test pattern having mathematical sequence. In such a situation where the change or addition of the hardware resources is made, it is necessary to accordingly modify the software to control the hardware that has been newly added or modified. This usually includes the process of transferring the appropriate data to internal registers in the newly added or modified hardware.
In the conventional technology, such a modification of the software in accordance with the change in the hardware is not easily carried out. For example, in such a situation, the conventional technology requires a complicated modification procedure of the software and thus involves long works. Further, to carry out a work for such a software modification, it is usually necessary to use the hardware which has actually been changed or added. Thus, it is desired in the industry to develop means for easily carry out the modification of the software in accordance with the change or addition in the hardware of the semiconductor test system prior to the actual change or addition of the hardware. It is also desired that such modification of software or the development of test program and its debugging associated with the change or addition of the hardware be made only by emulating such hardware without using the actually hardware to be added to the system.